1. Field of the Invention
The present invention relates to an arrangement of a knock sensor on an engine, for detecting knocking in the engine on a vehicle, such as a motorcycle. More particularly, the present invention relates to an arrangement of a knock sensor on a motorcycle engine at a rear portion thereof, configured and arranged so that the knock sensor is substantially surrounded and protected by other engine components.
2. Description of the Background Art
There are several known positional arrangements in which a knock sensor is arranged on a cylinder block of an engine. An example of such arrangement of knock sensor is disclosed in the Japanese Patent document JP-A-2003-322054, which discloses a knock sensor mounted on an engine of a four-wheeled vehicle, such as a car. The knock sensor of this reference is generally covered by a hood of the car. Therefore, such arrangement of the knock sensor does not generally require a protective cover to specifically cover the knock sensor.
However, when such a knock sensor is mounted on an engine of a motorcycle, it has conventionally been necessary to provide a separate protective cover for protecting the knock sensor (or the like) since an engine of the motorcycle is exposed to the outside environment, including inclement weather. On conventional motorcycle engines, the knock sensor is generally arranged on a side surface or on a front surface of a cylinder block of the engine. Such a conventional arrangement of the knock sensor typically requires a protective cover for protecting the sensor.
Further, in order to arrange the knock sensor on a rear surface of the cylinder block of the motorcycle engine, it is necessary to impose restrictions on arrangement of other required additional functional parts, such as a starter motor, which are usually mounted on an upper rear surface of a crankcase.
The present invention has been made to overcome such drawbacks. Accordingly, it is one of the objects of the present invention to provide an engine having a knock sensor arranged (disposed) thereon at a location which does not impose significant restriction on the arrangement of additional functional parts, e.g. a starter motor, arranged on an upper rear surface of a crankcase.